What I would do is just accept and allow people to climb up the slide--if it not busy enough to prevent it. What harm is there in it? The only problem with people going up the slide is if people are going down. Oh, and maybe people scratching your slide with their shoes--so make sure you have a nice metal slide. Maybe even provide a piece of burlap for people to use to slide down. People can hand it back up to the people at the top.

"The essence of tyranny is not iron law. It is capricious law." -- Christopher Hitchens

A slide that looks like it is made of sandpaper or some other abrasive while being absolutely smooth in reality might be fun to observe.

Savannah: I don't know what it is, but no thread here escapes alive. You'll get 1 or 2 real answers at minimum, occasionally 10 or 12, and then we flog it until it's unrecognizable and you can't get your deposit back.

On a lower tech note - they make linoleum tiles that are smooth, yet are printed realistically to look heavily textured like gravel, splintered wood, grass, etc...

Savannah: I don't know what it is, but no thread here escapes alive. You'll get 1 or 2 real answers at minimum, occasionally 10 or 12, and then we flog it until it's unrecognizable and you can't get your deposit back.